Studies on bacteriophage distribution: virulent and temperate bacteriophage content of mammalian feces

Dhillon, T. S.; Dhillon, Elvera K. S.; Chau, H C; Li, W K; Tsang, Arthur

doi:10.1128/aem.32.1.68-74.1976

Cited by 95 publications

(33 citation statements)

References 14 publications

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“…It is not even clear where lytic coli phage live under natural conditions. While we have found high densities of lytic coli phage (up to 10 5 per ml) in sewage treatment plants, they are relatively uncommon in feces (Dhillon et al, 1976).…”

Section: Discussionmentioning

confidence: 52%

Phage-Mediated Selection and the Evolution and Maintenance of Restriction-Modification

Korona

Levin

1993

Evolution

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Restriction-modification (R-M) was discovered because it provides bacteria with immunity to phage infection. But, is phage-mediated selection the sole mechanism responsible for the evolution and maintenance of these ubiquitous and multiply evolved systems? In an effort to answer this question, we have performed experiments with laboratory populations of E. coli and phage and computer simulations. We consider two ecological situations whereby phage-mediated selection could favor R-M immunity; i) when bacteria with a novel R-M system invade communities of phage-sensitive bacteria in which there are one or more species of phage, and ii) when bacteria colonize bacterial-free habitats in which phage are present. The results of our experiments indicate that in established communities of bacteria and phage, the advantage R-M provides an invading population of bacteria is ephemeral. Within short order, mutants resistant (refractory) to the phage evolve in the dominant population and subsequently in the invading population. The outcome of competition then depends on the relative fitness of the resistant states of these bacterial clones, rather than R-M. As a consequence of sequential selection for independent mutants, this rapid evolution of resistance occurs even when two and three species of phage are present. While in our experiments resistance also evolved when bacteria colonized new habitats in which phage were present, a novel R-M system greatly augmented the likelihood of their becoming established. We interpret the results of this study as support for the hypothesis that the latter, colonization selection, may play an important role in the evolution and maintenance of restriction-modification. However, we also see these results and other observations we discuss as questioning whether protection against phage is the unique biological role of restriction-modification.

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Section: Discussionmentioning

confidence: 52%

Phage-Mediated Selection and the Evolution and Maintenance of Restriction-Modification

Korona

Levin

1993

Evolution

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“…In the last 20 years, researchers have found that phage are much more numerous in many ecosystems than was traditionally thought and play a more central role in bacterial ecology (Fuhrman 1999;Ashelford et al 2000;Danovaro et al 2001;Breitbart et al 2003;Brabban et al 2005). The presence of phages in the guts of mammals (including ruminants) has been widely described (Dhillon et al 1976;Breitbart et al 2003;Callaway et al 2006;Raya et al 2006). Further, it has been suggested that phage in cattle help maintain microbial diversity and balance, allowing the ecology of the gut, particularly the rumen, to adapt to change (Klieve and Swain 1993;Swain et al 1996).…”

Section: Discussionmentioning

confidence: 99%

Prevalence of Escherichia coli O157 and O157:H7-infecting bacteriophages in feedlot cattle feces

Oot

Raya

Callaway

et al. 2007

Lett Appl Microbiol

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Aim: To estimate the distribution and prevalence of both Escherichia coli O157 and O157:H7‐infecting bacteriophages within a 50 000 head commercial beef feedlot. Methods and Results: Escherichia coli O157 was detected in ∼27% of the individual samples, distributed across seven of the 10 pens screened. In a simple initial screen to detect O157:H7‐infecting phages, none were detected in any pen or individual sample. In contrast, after a series of enrichment procedures O157:H7‐infecting phages were detected in every pen and in the majority of the samples from most pens; virulent bacteriophages active against E. coli O157:H7 were detected post‐enrichment from 39/60 (65%) of the feedlot samples, and 58/60 (∼97%) contained phage that infected E. coli B or O157:H7. Conclusions: The data we present here indicates that we may be grossly underestimating the prevalence of O157:H7‐infecting phages in livestock if we simply screen samples and that enrichment screening is required to truly determine the presence of phages in these ecosystems. Significance and Impact of the Study: Our data suggest that O157:H7‐infecting phages may play a role in the ecology and transient colonization of cattle by E. coli O157:H7. Further, this and previous data suggest that before starting in vivo pathogen eradication studies using phage or any other regime, test animals should be enrichment screened for phage to avoid erroneous results.

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“…Furthermore, it is not clear what the expected concentration of E. coli targeting phages is in human fecal samples. Previous studies indicate that plaque forming units (pfu) from human feces on E. coli is in the range of 10 1 -10 7 per gram, with a median concentration of~10 3 per gram 42,43 . Considering that the concentration of E. coli in human feces is in the range of 10 7 -10 9 per gram 44 , interactions between phages and the recording strain might be substantially less common than interactions between commensal E. coli and the recording strain.…”

Section: Discussionmentioning

confidence: 99%

Recording mobile DNA in the gut microbiota using an Escherichia coli CRISPR-Cas spacer acquisition platform

et al. 2020

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The flow of genetic material between bacteria is central to the adaptation and evolution of bacterial genomes. However, our knowledge about DNA transfer within complex microbiomes is lacking, with most studies of horizontal gene transfer (HGT) relying on bioinformatic analyses of genetic elements maintained on evolutionary timescales or experimental measurements of phenotypically trackable markers. Here, we utilize the CRISPR-Cas spacer acquisition process to detect DNA acquisition events from complex microbiota in real-time and at nucleotide resolution. In this system, an E. coli recording strain is exposed to a microbial sample and spacers are acquired from transferred plasmids and permanently stored in genomic CRISPR arrays. Sequencing and analysis of acquired spacers enables identification of the transferred plasmids. This approach allowed us to identify individual mobile elements without relying on phenotypic markers or post-transfer replication. We found that HGT into the recording strain in human clinical fecal samples can be extensive and is driven by different plasmid types, with the IncX type being the most actively transferred.

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Studies on bacteriophage distribution: virulent and temperate bacteriophage content of mammalian feces

Cited by 95 publications

References 14 publications

Phage-Mediated Selection and the Evolution and Maintenance of Restriction-Modification

Phage-Mediated Selection and the Evolution and Maintenance of Restriction-Modification

Prevalence of Escherichia coli O157 and O157:H7-infecting bacteriophages in feedlot cattle feces

Recording mobile DNA in the gut microbiota using an Escherichia coli CRISPR-Cas spacer acquisition platform

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